Air-brake.



No. 788,149. PATENTED APR. 25, 1905. D. F. SNYDER.

AIR BRAKE.

APPLICATION FILED vow. 8.1904.

3 SHEETS-SHEET 1.

' Auxiliary fiesevoir' Witnesses W I 759%; Inventor. g w by I I I ,4== Iv Htkomegs Witnesses (9% No. 788,149. PATENTED APR. 25, 1905. D. F.SNYDER.

AIR BRAKE.

APPLICATION FILED DOT. 8.1904.

3 SHEETS-SHEET 2.

l yafi entor;

1 Rttomegs PATENTED APR. 25, 1905.

D. P. SNYDER.

AIR BRAKE.

APPLICATION FILED 00w. 8,1904.

3 SHEETS-SHEET 3.

Witnesses Httomess NITED STATES.

Patented April 25, 1905. 1

PATENT DAVID F. SNYDER, OF HARRISBURG. PENNSYLVANIA, ASSIGNOR OF ONE-FOUR"II TO JOSEPH 0. SMITH AND \VILLIAM F. (IARMAN, OF I'IARRIS- BURG,PENNSYLVANIA.

AIR-BRAKE.

SPECIFICATION forming part of Letters Patent No. 788,149, dated April25, 1905.

Application filed October 8, 1904. Serial No. 227,678.

To It whom it 'lII/(LZ/ (07L0l77r5 Be it known that 1, DAVID F. Sxrnuu,a citizen of the United States, residing at llarrisburg, in the countyof Dauphin and State of 5 Pennsylvania. haveinvented a new and useful-'-\irl 3rake, of which the following is a specilication.

This invention relates to air-brakes, and has for one of its objects toprovide means where- 10 by a certain predetermined pressure of air maybe retained in the brake-cylimler in the event of accidental leakage ofany of the air connections.

A further object of the invention is to pro- 5 vide a safety devicewhereby should there be any accidental movement of the triple valve torelease position the brakes will not be wholly released, but will stillbe held under a predetermined pressure.

A still further object of the invention is to provide an air-brakemechanism in which provision is made for securing graduated red uctionof the braking pressure, so that after the brakes have been appliedeither for graduated 2 5 or emergency application they may be partlyreleased, a certain predetermined pressure being retained in thebrake-cylinder, and when the brakes are to be fully released the engi--neer has merely to move his brake-valve to 3 the full-release position.

A still further object of the invention is to insure the positiverelease of the brakes even where the movement to full-release positionis momentary, a portion of the air under high ,5 pressure being trappedor held in such manner as to insure the discharge of all of the air fromthe brake-cylinder.

A still further object of the invention is to provide a device wherebythe auxiliary reser- 4 voir may be recharged while the brakes are set,so that there may always be a sufficient quantity of air under pressurein the auxiliary reservoir to set the brakes immediately after release.

A still further object of the invention is to provide a simple form ofretaining and recharging mechanism which may be applied to existingair-brake systems without any change whatever in the construction of thetriple valve, auxiliary reservoir, brake-cylinder, or the enginecfisbrake-valve, the operation of the latter being precisely the same as atpres cut, and the engineer requiring no further instructions in the useof his valve.

'ith these and other objects in view, as will more fully hereinafterappear, the invention consists in certain novel features of constructionand arrangement of parts, hereinafter fully described, illustrated inthe accompanying drawings, and particularly pointed out in the appendedclaims, it being understood that various changes in the form,proportions, size, and minor details of the structure may be madewithout departing from the spirit or sacrilicing any of the advantagesof the invention.

In the accompanying drawings, Figure 1 is an elevation, partly insection, of an air-brake mechanism constructed and arranged inaccordance with the invention. Fig. 2 is a longitudinal sectionalelevation of the pressureretaining valve and controlling-valve. Fig. 3is a similar view with the parts in a different position. Fig. A is adetail perspective view of the controlling-valve and its piston. Figs.and 6 are views corresponding to Figs. 2 and 3, illustrating aslightly-modified construction. Fig. 7 is a detail perspective view ofthe valve and piston shown in Figs. and 6.

Similar characters of reference are employed to indicate correspondingparts throughout the several figures of the drawings.

In the drawings the auxiliary reservoir (1,

" triple valve 5, brake-cylinder c, and train-pipe (Zare all of theusual construction and are connected in the usual manner.

To the train-pipe is connected a casing 10, having at one end a cylinder11, in which [its a piston or diaphragm 12, that is exposed on one sideto train-pipe pressure. The casing 10 is in the form of an elongatedcylinth'ical shell closed at its outer end by an adjustable plug 13,over which [its a cap 1%, that is removed when the plug is to beadjusted. At the cylinder end of the casing the interior of the latteris faced to form two valve-seats and 16, and to the seat 15 extends apipe 17, leading from the triple-valve exhaust a suitable cut-01f valve18 being arranged in the pipe when it is desired to cut out the deviceforming the subject of the present invention, this valve being movableto permit direct communication between the brake-cylinder exhaust andthe outer air when necessary. The lower valve-seat 16 contains two ports19 and 20, one of which, 19, leads directly to the outer air, while theother is in communication with a casing 21, containing a spring-pressedretaining-valve 22, the tension of the spring being adjusted by asuitable nut 23, and under ordinary circumstances this valve is set toopen at a pressure of, say, twenty pounds, although this may beincreased or diminished in accordance with circumstances. Between thetwo valve-seats is arranged a slidable valve 2 1, that is secured to orformed integral with the piston 12 and is acted upon by a helicalcompression-spring 25, the outer end of which rests against the plug 13,so that the latter may be used for adjusting the stress of the spring.The outward stroke of the valve and piston 12 is limited by the head 26of the cylinder 10, said head being so arranged that the edge of thepiston comes directly into contact therewith and is positively stopped.

The port of the pipe 17 and the port 20, leading to the retaining-valve,are in direct alinement diametrically of the casing, and the port 27 ofvalve 2 normally assumes a position in direct alinement with said pipeand port, so that the brake-cylinder exhaust is normally incommunication with the casing of the retaining-valve. The valve isretained in running position by the spring 25, the latter being set at apressure corresponding to the pressure of air normally carried in thetrainpipe. For instance, on freight-trains a pressure of seventy poundswill be used, and the piston 12 and valve 24 would retain the normalposition, the piston yielding only when the pressure exceeds the normaltrain-pipe pressure.

In the upper face of the valve is arranged a port or passage 29, thatcommunicates with the port 27, and when the piston 12 is moved by excesstrain-pipe pressure the exhaustpipe 17 will be placed in directcommunication with the port 27 and exhaust-port 19, so that thebrake-cylinder exhaust of the triple valve will be placed in directcommunication with the outer air and may reduce the brakeeylinder toatmospheric pressure. The valve 22 may be of the character ordinarilyemployed as reducing-valves and set to yield under any desired pressure.

While the train-pipe may be connected directly to the head 26, it ispreferred to introduce in the connection an auxiliary-valve casing 30,having a seat for a check-valve 31. The check-valve is provided with astem 32, extending into a guiding-recess 33, formed in passengerservice.

check-valve is reduced to less than that within the casing 30, thecheck-valve will promptly close, the movement being assisted by thespring, and then if reduction continues the air in the chamber 30 willgradually reduce toward the train-pipe through a leakage-port 36, formedin the valve or in the valve-seat.

The device may be set to operate under any pressure and employed inconnection with the existing brake systems for either freight or Takingas an instance a seventy-pound train-pipe pressure, as used on manyroads for freight-service, the plug 13 is adjusted in order to preventmovement of the piston 12 from the position shown in Fig. 1 when exposedto a pressure of seventy pounds or less. The position shown in Fig. 1 isthe running position, and the triple valve is moved to such positionthat the brake-cylinder is in communication with the exhaust-port andthe pipe 17 and thus through the port 27 of valve 24 with theretaining-valve casing 21, and at this time the brake-cylinder pressuredoes not exceed the natural atmospheric pressure. When the brakes are tobe applied either for a graduated application or for an emergency stop,the engineer moves his valve to either the service or the emergencyposition and train-pipe pressure is reduced. This moves the triple valvein the usual manner, and air reduces from the auxiliary to the brakecylinder, the amount of such reduction depending on the reduction of thetrain-pipe pressure and the length the engineers brake-valx e is opened.The engineer will then usually place the brake-handle on lap and when itis desired to release the brakes will move the brake-handle to releaseposition in order to place the main reservoir in communication with thetrainpipe. This is the ordinary procedure, and the brakes will bereleased in the usual manner by moving the triple valve back to itsnormal position and placing the brake-cylinder in communication with theexhaust-port of the triplevalve casing. In carryingout the presentinvention, however, the engineers brake-valve is placed in runningposition and the train-pipe is grad ually recharged, so that there willbe no violent movement of the piston 12, the latter retaining theposition shown in Fig. 1, inasmuch as the train-pipe pressure will notexceed that to which the spring 25 is set. The triple valve will bemoved back to recharging position and the brake-cylinder will be placedin communication with the exhaust-port and exhaust-pipe 17, the lattercommunicating, as before described, with the port 27 of valve 24 and theretaining-valve casing 22. This permits reduction of the brake-cylinderpressure to an extent determined by the adjustment of the spring 23 ot'the retaining-valve, this being usually set to resist twenty-poundspressure, and when brake-cylinder pressure has been reduced to thispoint the valve will close and the brakes will still be held under thetwenty-pounds pressure. At the same time the auxiliary reservoir isrecharging through the leakage-groove in the usual manner, and in ashort time the engineer has on hand a sufiicient quantity of air for animmediate reapplication of the brakes. To fully release the brakes, theengineer then moves his brake-handle to full-release position, and themain reservoir being placed in direct communication with the train-pipeasudden surge of air under pressure will occur through the pipe, and thepistons 12 thoughout the train will be moved to the position shown inFig. 2, thus placing the exhaust-pipes 17 in communication with theexhaust-port it) through the medium of the diametrical port 27 of valveQT and allowing the brake-cylinder to reduce to atmospheric pressure,thus releasing the brakes. The discharge of air from the brakecylindermay occupy some little time, and the main-reservoir pressure may not besulticient to hold the pistons l2 in the position shown in Fig. 2 for alength of time sutiicient for the purpose. The check-valve 31 here comesin play. The excess train-pipe pressure passing beyond the check-valveis trapped in the casing 31), and as soon as the train-pipe pressure isreduced the valve closes and the pressure is retained in the casing 30and gradually reduces through the leakage-port 36 and permits the pistonto reassume the position shown in Fig. 1, but the movement of saidpiston and valve being so gradual that there is opportunity for all ofthe air under pressure in the brake-cylimler to escape.

One of the principal advantages gained from the employment of a deviceof this charactor is that in the event of any accidental leakage of anyof the parts after the brakes have been set the brakes are still heldunder a predetermined pressure twenty pounds and will not be fullyreleased. Leakage may at times occur through the rotary of the engineersbrake-valve to an extent sutiicient to recharge the train-pipe and movethe triple valve to release position, and in ordinary service the brakeswould be fully released. In the present case, however, the brakes wouldstill be held under a pressure of twenty pounds, more or less, andleakage is also likely to occur in a plain triple from the four-way cockor from t'aulty piston-packing; but in all cases where there is atendency to accidentally release the brakes at'ter being set the deviceforming the subject of the present invention will still hold the brakesunder the previouslydetermined pressure.

in Figs. 5 and 6 is illustrated aslight modi- Iication of the inventionwherein the piston I2 is subjected to air-pressure on both sides. Inthis case the casing 10 carries at one end a cylinder 11 incommunication on one side with the train-pipe and on the opposite sidewith the casing 10'. The brake-cylinder exhaust-pipe 1T communicatesdirectly with the interior ofthe casing, and when the triple valve ismoved to exhaust position the air flowing through the pipe 17 will exertsome pressure on that face of the piston opposite to the'lace exposed totrain-pipe pressure. In the casing is a port 20', communicating with acasing 21, that contains a retaining-valve 22, that may be adjusted inorder to open at twenty pounds, more or less, as desired, and thebrake-cylinder cannot reduce below this pressure when the parts are innormal position. In the easing is a port 19, that is normally closed bya valve 24:, carried by and moving with the piston 12. This valve is ofsuch construction as to permit the tree passage of air between thecasing and the cylinder, and in its under side is a port 40, which mayat times assume the position shown in Fig. 5. \Vhenitis desired to fullyrelease the brakes, the engineers brake-valve is moved to full-releaseposition and the piston '12 moves to the position shown in Fig. 6, thusuncovering the port 19 and permitting the brake-cylinder to exhaust tothe atmosphere.

The device is of especial value in case of leakage of the auxiliaryreservoir, where a triple valve always moves to release position underthe train-pipe pressure. Under ordinary circumstances this wouldimmediately release the brakes; but in the present case the brakes willstill be held under the previouslydetermined pressure.

Having thus described the invention, what is claimed is---- 1. .Inair-brake mechanism, a cylinder, one side of which is connected to thetrain-pipe, a piston arranged in the cylinder and exposed to train-pipepressure, a valve-casing connected to the cylinder at that side oppositethe train-pipe connection, and having ports, one of which is incommunication with the exhaust-port ot' the triple valve, and anotherwith the outer air, a valve normally closing the latter port, apressure-rotaining valve connected to the casing and normally in treecommunication with the interior thereof, and with the port leading fromthe exhaust-port of the triple valve, a valve arranged in the casing, aspring also arranged in the casing and acting to prevent any movement ofthe piston under ordinary train-pipe pressure, saidspring alsomaintaining the valve in a position to prevent communication between theinterior of the casing and the outer air.

2. In air-brake systems, avalve for controlling the exhaust of air fromthe brake-cylinder, a piston connected to said valve, a casing in whichsaid piston is contained, said cylinder being connected to thetrain-pipe, and a my own I have hereto affixed my signature incheck-viflve arranged in the train-pipe1 conriecthe presence of twoWitnesses. tion anc opening in the direction of t e ey inder, therebeing aleakage-portfor permitting DAVID SNYDER 5 gradual reduction ofpressure between the Witnesses:

check-valve and the cylinder. Jos. 0. SMITH,

In testimony that I claim the foregoing as EMORY H. BAGLEY.

